NATURAL PHILOSOPHY. 211 



of the raining fluid, not only so that co-operation at ordinary tempera- 

 ture should go on, but so that condensation may again take place in 

 the ordinary air. Not only mast this qualitative arrangement exist, 

 but also a quantitative one, since the quantity of rain best sufficing to 

 the aggregate organic need, is exactly a certain definite number of 

 inches per annum. Now water is doubtless the only known liquid 

 which could by possibility answer these definite mechanical conditions. 

 Hence we say that there is a peculiarly clear evidence of design: 

 First, in making a fluid which could under our cosmical conditions 

 undergo the raining round ; and secondly, in its being on the earth 

 in so exactly the quantity best meeting the aggregate organic needs. 

 Ether, quicksilver, or any other known fluid, could not in any possible 

 arrangement of quantity, supply this primary cosmical necessity. Now 

 when we reflect how many are the instances in Avhich the terrestrial 

 elements simple and in combination exist in strict accommodation 

 to organic needs, both qualitatively and quantitatively, the cumulative 

 evidence of design, is as apparent as that furnished by a locomotive 

 or a cotton-mill. Not only is organic life found in strict relation to 

 the earth, but the earth is also primarily constituted in strict relation 

 to organic life. Let whoever doubts this, studv the extremely slender 



* J 



a priori chance that a drop of rain, of any liquid, should ever fall 

 upon the earth ; and let him but picture the total lack of all animal 

 life which must have followed any cast of the die other than that really 

 existing. Life, without fluid circulation, is totally inconceivable by 

 the mind of man ; and exactly to determine the appropriate kind and 

 quality of liquid, as has been done in the real frame of nature, was a 

 problem of pure and absolute intellection, transcending the grasp of 

 every mind save the all- wise creating designer. 



METHOD OF OBTAINING A PERFECT VACUUM. 



The following communication appears in the February number of 

 Brewster's Journal, from Dr. Thomas Andrews. 



The space left vacant in the upper part of a long glass tube, which 

 after being filled with mercury is inverted in a basin of the same 

 metal, affords the nearest approach to a perfect vacuum which has 

 hitherto been obtained. It is true that it contains a little mercurial 

 vapor at the ordinary temperature of our summers, and probably also 

 at lower temperatures ; but the quantity is exceedingly small, and its 

 influence in depressing the barometric column must be altogether in- 

 appreciable. Besides the mercurial vapor, a trace of air may gener- 

 ally be detected even in tubes which have been carefully filled, and in 

 which the air interposed between the glass and mercury has been ex- 

 pelled by ebullition. This is best observed by inclining the tube till 

 the mercury comes into contact with the upper end, when the air that 

 may have been diffused through the vacuum will be seen collected in 

 a small bubble, but greatly rarefied. 



The Torricellian vacuum leaves therefore scarcely anything to be 

 desired in point of completeness ; but it is unfortunately 'applicable to 



